1. Field of the Invention
The present invention relates to electronic and/or plasmonic circuit elements and, more specifically, to surface-plasmon signal detectors.
2. Description of the Related Art
This section introduces aspects that may help facilitate a better understanding of the invention(s). Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art and/or what is not in the prior art.
Surface plasmons (SPs), also often referred to as surface-plasmon polaritons, are surface-bound waves that can propagate, e.g., along a metal-dielectric interface or along a metal-vacuum interface. An SP can be qualitatively viewed as a combination of an electromagnetic wave and an associated charge-density wave. The electromagnetic wave propagates along the interface due to its interaction with free surface charges of the metal. The interaction also causes the surface charges to oscillate in resonance with the electromagnetic wave. The combined physical entity created via this resonant interaction, i.e., an entity including a charge-density wave and a corresponding electromagnetic wave, is an SP. A detailed description of certain physical properties of SPs can be found, e.g., in an article by W. L. Barnes, et al., entitled “Surface Plasmon Subwavelength Optics,” published in Nature, 14 Aug. 2003, v. 424, pp. 824-830, the teachings of which are incorporated herein by reference in its entirety.
SP signals find use in optical communication systems, e.g., as described in U.S. Pat. Nos. 7,027,689, 7,039,277, and 7,039,315, each of which is incorporated herein by reference in its entirety. To carry data, SP signals can be modulated at relatively high modulation speeds, e.g., on the order of 100 GHz. However, SP-signal detectors capable of appropriately responding to the full range of available modulation speeds are not yet sufficiently developed.